Hydrochloride of 2-amino-2-[2-[4-(3-benzyloxyphenylthio)-2-chlorophenyl]-ethyl]-1,3-propanediol (hereunder referred to as the “compound of the present invention”) is a compound having a substituted diaryl sulfide structure and having an excellent immunosuppressive action and there has been reported that the compound of the present invention is effective for the treatment of the autoimmune diseases such as chronic rheumatoid arthritis (see Patent Document 1).
Patent Document 1 discloses a method for the crystallization of the compound of the present invention which comprises the step of crystallizing the compound through the addition of an ethyl acetate solution of hydrochloric acid to a methanol solution of the compound (see Example 36). In addition, Patent Document 2 discloses a method for the crystallization of the compound of the present invention, which comprises the steps of adding a 6 mole/L of hydrochloric acid to a solution of the compound of the present invention in ethyl alcohol and then adding ethyl acetate to the resulting solution (see Example 4). These methods are ones in which hydrochloric acid is dissolved in ethyl acetate and then the resulting hydrochloric acid solution is added to a solution of the compound of the present invention in an alcohol; or hydrochloric acid is added to an alcoholic solution of the compound of the present invention and then ethyl acetate is added to the resulting mixture.
Patent Document 1: WO 03/029205, Pamphlet;
Patent Document 2: WO 06/041019, Pamphlet.